Barlow v Eyepiece

[noeliam]

Took a little trip to the local Astro shop yesterday to begin the upgrade on my 200P, Having bought it about 6 weeks ago i have enjoyed looking at Saturn and the Moon with the 2 eyepieces provided and intended to get a barlow as my 1st upgrade, after chatting with the shopkeeper and getting answers to a few questions i decided instead to spend a bit more money and get a Celestron X-Cell LX 7mm eyepiece. I must say what a nice piece of kit, looks 10/10 feel 10/10 and i like the heavy feel to it too. Looking forward to having a look with this eyepiece.

So advice time guys, did i do the right thing rather than getting the barlow ? should i still get one or am i better spending a tad more each month and building a good collection of eyepieces?

Thanks all

Steve.

[Knighty2112]

Depending on what your two stock EP sizes were (most tend to be 20mm & 10mm), with a 2x Barlow you would have only achieve an extra magnification with the 10mm become in effect a 5mm EP, as the 20mm would show what you see currently with the 10mm EP on its own. A 7mm X-Cel is pretty close to the 5mm, and will be much better quality than the 2 stock EPs, so a good choice to start off with a better EP. You can always add a decent Barlow later on.  

[noeliam]

Thanks Knighty good to know i made a good choice, I currently have a 10mm & 25mm as standard, there ok and do the job, Lets hope for clear skies over Yorkshire tonight :-)

[rockystar]

I think you've made a good choice. I prefer not to use a barlow, but that's just my preference, others love them, or a powermate, but they tend to say to buy a decent one and don't compromise.

if you do get another eyepiece next, consider how it would Barlow, so don't get a 14mm and a 2x barlow, as it would be the same as your 7.

hope you get some clear skies to try it out

 

[Charic]

The X-Cell LX  has good reports, though I have never tried one myself, my  first upgrade was an 8mm BST Starguider, the rest followed.

A Barlow can be  a worthwhile  addition to your eyepiece collection, but do ensure there are not too many overlaps in focal range.  Having only an 8, 16 and 32mm for example and a 2x Barlow only affords the 'extra' 4mm from the 8mm!

Having say  8 12  and 20mm EPs gives you the extra 4,6 and 10mm to play with?

I have three Barlow's, Celestron (never used -  Plastic lens  I think?) A Meade and my favorite the Skywatcher Deluxe, whereby I only use the  lens cell  without the silver barrel. The cell is screwed directly into the base of the eyepiece giving me about 1.6x Barlow, but having more than enough eyepieces at present, the Barlow often stays in the case.

Out of the two Skyliner supplied eyepieces, the 25mm works reasonably well, but less field of view than my BST's and because I like looking at M31 from a darker site, I needed an even wider fov, so opted for a 32mm 70° Skywatcher Panaview.

[Knighty2112]

1 hour ago, noeliam said:

Thanks Knighty good to know i made a good choice, I currently have a 10mm & 25mm as standard, there ok and do the job, Lets hope for clear skies over Yorkshire tonight :-)

Fingers crossed, although I am away for work so won't get a chance to do any astronomy (unless I take my binos with me) until next weekend again. Hope it's clear for you to get out more with your new EP.  

[Rick Towns]

Personally, I am not a Barlow guy - I just have a nice spread of eyepieces that cover all the magnification ranges that I am interested in with my scope. Truthfully, most of the time you only need 3 eyepieces: low, medium and high power. I wound up with 6 which give me 63x (32mm), 100x (20mm), 133x (15mm), 182x (11mm), 250x (8mm) and 333x (6mm). If I were just to use 3, I would probably go with the 32mm, the 15mm and the 8mm. But to each their own. When I started building this eyepiece set, I decided I wanted "minimum glass" between my eye and the sky, which meant only 4-element eyepieces (Plössls and an Ortho). I feel adding a Barlow (especially a 3-element APO Barlow) just turns my 4-element eyepieces into 7 element eyepieces.

Many people are very happy with more complex eyepieces and lots are very happy using a Barlow. As others have said, perhaps a Barlow would make sense for you if it provided you and additional magnification or two that you want. But, if it were me, I'd buy more eyepieces.

[Mak the Night]

The main advantage of using a Barlow or amplifier is that you can decrease the focal length of the eyepiece yet maintain its field stop size and field of view to make observing more comfortable. Not all eyepieces 'Barlow' well however.

Like most things in amateur astronomy the efficacy of the Barlow in use is often directly proportional to the amount you're prepared to spend on it. This isn't necessarily a hard and fast rule though. The first three achromatic Celestron 2x Barlows in the top row here are comparatively inexpensive and can produce good results without overly degrading the image.

Although I've customised the Omni and standard Celestron kit Barlows so that they now have detachable Barlow elements like the Celestron T-Adaptor/Barlow combination. The apochromatic X-Cel Barlows and TeleVue Barlow/amplifiers on the bottom row are more expensive and I acquired this diverse collection for slightly different tasks. TeleVue don't believe in 'shorty' types of Barlow but these short Barlows often work better for me in diagonals. The short TS Optics (GSO) 2.5x Barlow at the end of the top row is sold under a variety of brand names (and prices) but is a very competent Barlow for what it cost. If I had to recommend one good all round Barlow that was cost effective. it would be that.

Revelation 2.5x

 

[Mr Spock]

My preference is always to use an eyepiece without a Barlow. No matter how good the Barlow is, putting extra lenses in the optical path is going to degrade the image to some extent.

[John]

8 minutes ago, Mr Spock said:

My preference is always to use an eyepiece without a Barlow. No matter how good the Barlow is, putting extra lenses in the optical path is going to degrade the image to some extent.

I've reached this point now as well. I've owned and used some excellent barlows and the superb Tele Vue Powermates but I do prefer "just the eyepiece" now

 

[Mak the Night]

46 minutes ago, Mr Spock said:

My preference is always to use an eyepiece without a Barlow. No matter how good the Barlow is, putting extra lenses in the optical path is going to degrade the image to some extent.

Although I would agree in many ways, it's often more practical to turn something like a small 6mm orthoscopic into a 3mm one with a good Barlow. After all, this is essentially what most wide view eyepieces do anyway.

I also doubt my TeleVue Barlows degrade the image enough for anyone human to detect. I can't speak for Vulcans of course.

[Piero]

I think it is more down to one's preferences. 

My only complains about using a barlow is the loss in parfocality and the increase length of ep+barlow. Tele-extender and powermate solve the first issue. Some barlow can somehow solve the second on diagonal-free telescopes.

Some eyepieces barlow/powermate well, others don't. I believe that when people complain about image degradation using a barlow, they either used an eyepiece with didn't match well, or used a barlow that is not premium or that the seeing was just not up to the job. A lot of modern eyepieces containing many lenses inside are built with a barlow concept in mind. If a barlow would degrade the resulting image, then all these eyepiece would not be successful which is clearly not the case.

A TV powermate is a very good tool and likely preserves the quality of eyepieces up to Tele Vue quality to me. What I mean is that if you put a Nagler 13mm T6 on a Powermate 2.5x you get a Nagler 5.2mm T6 (undetectable degradation), and if you put a Delos 12mm, you get a Delos 6mm (undetectable degradation). On the other hand if you put an eyepiece of better quality, you might detect some image degradation though. In the end, these tools add glass (or filters). To not spot image degradation, you need to go for high quality, be reasonable with the magnification to achieve and make sure the seeing is up to. 

Just my opinion of course.

[Stu]

1 hour ago, Mak the Night said:

The main advantage of using a Barlow or amplifier is that you can decrease the focal length of the eyepiece yet maintain its field stop size and field of view to make observing more comfortable. Not all eyepieces 'Barlow' well however.

Like most things in amateur astronomy the efficacy of the Barlow in use is often directly proportional to the amount you're prepared to spend on it. This isn't necessarily a hard and fast rule though. The first three achromatic Celestron 2x Barlows in the top row here are comparatively inexpensive and can produce good results without overly degrading the image.

Although I've customised the Omni and standard Celestron kit Barlows so that they now have detachable Barlow elements like the Celestron T-Adaptor/Barlow combination. The apochromatic X-Cel Barlows and TeleVue Barlow/amplifiers on the bottom row are more expensive and I acquired this diverse collection for slightly different tasks. TeleVue don't believe in 'shorty' types of Barlow but these short Barlows often work better for me in diagonals. The short TS Optics (GSO) 2.5x Barlow at the end of the top row is sold under a variety of brand names (and prices) but is a very competent Barlow for what it cost. If I had to recommend one good all round Barlow that was cost effective. it would be that.

Revelation 2.5x

 

A question Mak, why so many barlows? Do you use them all?

[Rick Towns]

4 hours ago, Stu said:

A question Mak, why so many barlows? Do you use them all?

Maybe he stacks them all and gets 3000x from a TV N31! LOL! Lot's of eye relief at FULL POWAH!!!! (to quote Jeremy Clarkson!)

[ronin]

People tend to have different opinions, I prefer to use eyepieces and not to include a barlow. Likely as when I initially took up this hobby the quality of accessories was a bit questionable so you tended to have the least number of bits in that was required. Same with a zoom eyepiece, they were a "joke" years ago, but they have improved a lot to the extent that people will recommend getting one these days. Times they are a changing.

Mind tends to work along the lines that is an eye piece degrades an image to 90% and a barlow also degrades to 90% then Barlow+Eyepiece means 90%x90% = 81%. Will say that optical accessories have improved a lot but the thought is sort of ingrained and it ain't coming out.

The other reason is that to swap bits around will mean that at some time I am likely to have barlow, "old" eyepiece and "new" eyepiece in my hands all at once. Only have 2 hands and they do not work that well. Especially at night, in the dark and when cold.

So it is individual eyepieces for me.

I equally have the idea that if you bought a barlow you would still end up with something like the set of X-Cel LX's as well.

[mikeDnight]

Something that's worth remembering is that many high end multi element short focal length eyepieces already have a Barlow built into their design. The majority of modern barlows are generally very good and can be of real benefit when using simpler eyepieces, but if youre already using a 7 or 8 element eyepiece, adding two or more elements may begin to dull the image. The only image amplifier I've ever used that was utterly transparent no matter what eyepiece was being used was Takahashi's five element extender Q. It's two drawbacks are that it is hellishly expensive and it only fits Tak scopes, but its a match made in heaven.

Mike

[noeliam]

What i like about this site is there is always a difference of opinion, some like some don't, some use some don't Great feedback and as always good explanations as to what and why. Thanks all for the edumacation lol

[John]

32 minutes ago, mikeDnight said:

Something that's worth remembering is that many high end multi element short focal length eyepieces already have a Barlow built into their design. The majority of modern barlows are generally very good and can be of real benefit when using simpler eyepieces, but if youre already using a 7 or 8 element eyepiece, adding two or more elements may begin to dull the image. The only image amplifier I've ever used that was utterly transparent no matter what eyepiece was being used was Takahashi's five element extender Q. It's two drawbacks are that it is hellishly expensive and it only fits Tak scopes, but its a match made in heaven.

Mike

Those are good points Mike.

With a quality eyepiece, the elements used to deliver the focal length and extend the eye relief (usually positioned within the eyepiece barrel) should part of the overall design of the eyepiece rather than a generic barlow or smyth lens arrangement. To me this means using specifically matched glass types, lens prescriptions, coatings and spacing between the upper and lower lens assemblies and within the lower assembly.

A barlow / Powermate / Telextender will be designed to work with a wide range of eyepiece designes so, out of necessity, will be a generic design and there will, on occasions, be some small compromises here and there.

It's interesting to compare the optical layouts of the Pentax XW range as an example and how they differ across the focal lengths as the optical designer uses differing designs to deliver the focal lengths, sharp FoV and 20mm of eye relief in each focal length. Pentax also, unsually, used special coatings on the cemented lens surfaces as well, I assume to maximise light through put and minimise scatter. I believe that this approach is being adopted by some other premium brands now as well:

 

[Paz]

I think getting a shorter focal length of a higher quality as you have is a fine way to go.

 

 I've got both a Barlow and a lower mate and ultimately after lots of testing and getting a feel for what suits me I am coming down on the side of having the right eyepieces such that I don't need an amplifier.

Mostly this is driven by keeping it simple in the field - balancing, doing sums in my head about what field of view I'm looking at, less complications when changing EPs, etc. But there are plenty of  circumstances where a pm is  very helpful, e.g being an Ethos force multiplier!

To be fair the TV power mate is ridiculously good, I can't tell from the view that it is there.

[Jimtheslim]

If you had purchased a barlow, even a decent one and used that with the stock EP's you'd have been disappointed. As these tend to be fairly weak performing eyepieces in comparison to something like a Celestron Xcel, all the barlow would do is amplify the imperfections. The 7mm Xcel should be a fine eyepiece to be getting on with. Treat it well and if you decide you don't like it after a while then you can always sell it without loosing much money.

I keep thinking about buying a barlow, but always prefer to look for eyepieces instead. In fact, if I were you I would look at upgrading your 10mm before buying a barlow as your next purchase. I went for a Baader Classic Ortho 10mm and this is by far my favourite eyepiece (I also own the 7mm xcel) as seeing conditions rarely allow for higher magnifications and the 10mm just always seems to be my go-to and find myself looking into this for hours. If eye relief isn't a difficulty and you don't mind a smaller field of view then I would definitely look into one of these next.